Frequently, manufacturers of corrugated paperboard boxes are called on to supply boxes wherein an opposed pair of walls are comprised of two plies. For example, a box of this construction may be required in order to provide high stacking strength whereby a number of filled boxes may be stacked, one upon the other.
Whatever the reasons which necessitate such a box construction, the initial user of such a box is faced with the difficulty of quickly and efficiently assembling the box from an initially flat blank. In general, the desirability of providing a machine for automatically assembling a box from a flat blank has been recognized by the prior art relating to box making machinery. Illustrative of the prior art in this regard are U.S. Pat. Nos. 2,921,506, 1,287,032, 2,846,929 3,065,679, 2,132,859, 2,371,046, 3,741,084, 2,196,440, 2,741,957 and 3,125,007. Although all these patents disclose box making machinery, it will be seen upon close inspection that the machines disclosed in each of these patents tend to become more complex when the machine has to perform the function of forming a box having a double ply wall. Part of the complexity reflected by the machines disclosed in these patents is, perhaps, attributable to the typical prior art approach of endeavoring to substantially simultaneously form a box and form box walls which have a double ply.
Another complicating factor, which may not be evident from a review of these patents, is the machine design difficulty which arises when it is required to provide a machine for forming a box having double ply walls and wherein the depth of the box is substantial and the interior or reinforcing plies of the box extend over the entire height of the box. As may be evident upon some reflection, it becomes increasingly difficult to automatically form a box having double ply walls when the box has a significant depth and the interior ply extends over the entire height of the box.
The prior art patents identified above are particularly instructive to the extent that they appear to reflect a failure by the prior art to conceive of a machine having the specialized function of folding only the box flaps which ultimately form the interior reinforcing plies of a box having two ply walls. Thus, one attribute of my invention is that, in the preferred embodiment thereof, a machine is provided which is particularly adapted to the task of forming a box of the type heretofore described wherein the machine is initially supplied with a formed, open top box having upwardly extending flaps.
The utility of my invention is particularly evident with respect to a box construction wherein opposed walls have a two ply thickness and the interior or reinforcing plies are disposed in planes which are downwardly and outwardly inclined (anticlinal) and wherein there is a flat panel section connecting the top edges of respective pairs of wall plies. Typically, prior art machines lacked the capability of automatically erecting such a box, i.e., prior art machines generally have been designed to erect a more simple box construction wherein any interior reinforcing plies are vertically disposed and are positioned adjacent to the exterior side walls. One of the difficulties encountered in erecting a box construction of the former type is that each interior or reinforcing ply must be rotated through an angle greater than 180.degree.. Essentially, this constraint forecloses the use of such simple machine design expedients as pivotally mounted folding arms, i.e., it is generally difficult to employ a folding arms in a manner which will result in the rotation of a flap through an angle greater than 180.degree..
As hereinafter will be apparent, my invention is characterized by a relatively simple but efficient machine for accepting an open top box having upwardly extending flaps and folding or positioning the flaps within the box so as to provide reinforcing plies. Because of the capabilities of a machine embodying my invention, no substantial problem is presented when the reinforcing flaps of a deep box are substantially equal to the height of a box or if such flaps have to be folded through an angle greater than 180.degree..